Corvette C7 SR Strange to tune?

Hi guys,
I’m having a complete nightmare tuning this car. I brought the pack for this car as I see someone set a blistering time on Road America a few days back.
I needed a good tune for Road America so I’d thought I’d give it ago. So far i can hit the low 02.09.000 which don’t seem to be good enough… My specific problem is I think down to the gearing the 7th gear seems to throw every thing out… I know how to gear a car on forza (well at least I did until now) I have the arch on the chart in the tuning section and it’s nice arch shape. The problem is that it seems to struggle getting the power down in places. Specifically in the 3rd to last corner and the last corner before the main straight.
I’m not very good with American Muscle and it don’t seem to rev that high so again a presume it’s all toque. Putting higher cams in don’t do it any justice what so ever it just revs and nothing comes of it. I’ve tried stiffening the ARB’s suspension and damping to no success. Anyone got any ideas on how I can just squeeze a few tenths out of this car?
Also I have tyre wear on for tuning just because it adds a little bit flair going around a track do many times the corvette seems to eat tyres for breakfast any ideas on that would be appreciated. Many thanks

Start with a little gradual increase in rear ARB?

You have explained the problem yourself …go +1 gear up on each corner using the torque instead of ripping the nuts out of the engine plus u will get better traction n drive coming out…or strectch the box so u dont use 7th…if all else fails Tcs on …

Ok I’ll try it but I’m already taking the last corner in third. 4th seems to excessive which leaves 5th and 6th gear down the straight as the current tune I’ve got does not reach 7th down the main straight? Do I tune to bring 7th gear into play if I take the last corner in 4th? Sorry for the questions it’s baffled me.
As for the ARB’s they’re tweaked as much as I can with out loosing the back end of really badly understeering.

Yeah just run 7th on the back straight…or still run 6th but have longer ratios in 3456 gears…

Yep got ya I’m in the high 02.08.000 consistently now. It’s like driving a diesel… Thanks for your help.
I suppose that 7th gear would come in handy for Le Mans.